This invention relates, in general, to fabrication of optical devices and, more particularly, to fabricating optical star couplers.
This application is related to U.S. Pat. No. 5,265,184, issued on Nov. 23, 1993, bearing Ser. No. 07/889,335, titled MOLDED WAVEGUIDE AND METHOD FOR MAKING SAME, filed on May 28, 1992, which is hereby incorporated by reference herein, and to U.S. Pat. No. 5,265,184, issued on Nov. 23, 1993, bearing Ser. No. 08/019,731, titled MOLDED WAVEGUIDE WITH A UNITARY CLADDING REGION AND METHOD 0F MAKING, filed on Feb. 19, 1993, now U.S. Pat. No. 5,313,545.
At present, fabrication of an optical star coupler is achieved either alone or in combination with photolithographic and etching techniques, both of which are expensive and difficult to control. Additionally, while both fabrication techniques are extensively used in a semiconductor art, use of both of these fabrication techniques for fabricating star couplers in high volume manufacturing environment are needlessly complex and expensive.
Briefly, as practiced by one method in the prior art, a photolithographic polymer film is spun onto a silicon substrate. Portions of the photolithographic film are subsequently exposed, developed, and etched, thereby removing portions of the silicon substrate. The remaining photolithographic film subsequently is removed. Once the photolithographic film is removed, a silicon dioxide (SiO.sub.2) layer is deposited onto the etched silicon substrate, thereby filling the channels with SiO.sub.2 that were previously etched into the silicon substrate. The oxide film is then planarized by any suitable method so as to bring the silicon dioxide and the substrate into equal planarity, thereby generating waveguides or core regions in the silicon substrate.
However, the briefly outlined processes described hereinabove, are complicated, difficult to control, and unnecessarily expensive. Further, it should be noted that each additional processing step incurs an additional cost, as well as presenting an opportunity to induce defects into the star coupler.
It can be readily seen that conventional methods for making star couplers have severe limitations. Also, it is evident that the conventional processing uses a plurality of steps which are not only complex and expensive, but also are not efficient and effective for high volume processing. Therefore, a method for making the star coupler that provides a reduction in the number of steps required, reduces cost, and simplifies the processes necessary for making a star coupler would be highly desirable.